Dolly assemblies are well known as an automotive accessory for supporting vehicle tires. Typical dolly assemblies have a relatively heavy frame unit that is mounted on a set of four wheels. In order to position the dolly assembly under a vehicle tire, an auxiliary jack is needed to raise the vehicle. These types of dolly assemblies are undesirable due to the extra time and effort it takes to properly position and operate the auxiliary jack, as well as positioning the dolly assembly under the vehicle tire. There is also an additional cost associated with having to purchase the auxiliary jack. Further, due to the weight of these types of dolly assemblies, they are often difficult to transport.
Other known dolly assemblies have tried to alleviate the above disadvantages by providing caster mounted frame members that are connected together by a shaft. The shaft includes a crank handle which can be operated to move the frame members together, with frame members contacting the outside surface of the vehicle tire. As the frame members move together, the vehicle tire becomes supported by the frame members. While this type of arrangement is relatively lightweight and portable, the frame members do not have a sufficient structural strength to lift a vehicle tire while it is still mounted to the vehicle, thereby necessitating an auxiliary jack to initially support the weight of the vehicle.
Other known dolly assemblies have tried to eliminate the need for the auxiliary jack by providing a dolly assembly with a lifting mechanism. An example of this type of dolly assembly is a caster mounted U-shaped frame member with integral roller assemblies for contacting an outside surface of the vehicle tire. A lever cooperates with notches to drive arms the roller assemblies toward each other, thereby engaging vehicle tire and lifting it. While this type of arrangement does not require the use of an auxiliary jack, it is awkward to use as it requires constant resetting and releveraging of the lever on the frame member to successively drive the roller assemblies against the vehicle tire to lift it. Further, because of the constant resetting, this type of dolly assembly takes a significant amount of time to operate.
Another known combination dolly and jack assembly includes a pair of dolly carriages mounted on small wheels and having shoes for engaging a vehicle tire. The dolly carriages are connected together by a jack screw and by pivoting brace arms. The brace arms are further secured to a clamp that engages an axle hub of the vehicle tire. In operation, the shoes are positioned under the vehicle tire and connected to a stationary part of the vehicle by adjustable links. The clamp is then secured to the axle hub. The jack screw is operated to move the dolly wheel and shoes together, thereby lifting the vehicle tire. Once the vehicle tire is lifted, tumbuckles on the adjustable links are adjusted to properly support the vehicle tire. While an auxiliary jack is not required, the assembly has numerous components which increase manufacturing costs, and the possibility of a assembly failure. Further, the assembly requires a significant amount of time to be properly positioned on the vehicle tire and different tools for adjusting the tumbuckles and operating the jack screw.
Yet another type of dolly assembly is known in which a coaxial pair of vehicle tires are supported while the tires remain on the vehicle. With such an assembly, a pair of dolly bases, each of which are mounted on dolly wheels, are placed on the outside of each tire and two cross arm assemblies are extended transversely between the vehicle tires to connect the two dolly bases together. A lifting means is associated with the cross-arm assemblies to lift the cross-arms into engagement with the vehicle tires. While the assembly is useful for towing vehicles, it is not designed for supporting a single vehicle tire. Further, the cross-arm assemblies are relatively heavy, thereby making it rather difficult for an individual user to operate. Additionally, the assembly requires a significant amount of time to operate as it involves properly positioning the dolly bases, attaching the cross arm assemblies, and actuating the lifting means.